Martin J. Dougherty

“The most vital weapons at the disposal of a special forces soldier are his intellect and his mental toughness. Sometimes it all comes down to 'who wants it most', i.e. whoever is more willing to keep fighting and trying to survive. Being able to keep your head and look for advantages or escape routes is a big plus too.
Getting into 'survival mode' requires shifting mental gears when you need to. Good training helps with this as well as giving you the skills you need, but ultimately the will that drives your bid to survive is yours.
If you give in to fear or go into denial, pretending that it is not happening, then you will fail. Instead you must accept that it IS really happening and deal with it. So if you find yourself thinking, "What's he going to do to me?', you have to force yourself to answer, 'Nothing. I'm not going to let him.'
If you have done all you can to avoid trouble and it finds you anyway, then it is down to you to make a way out of the situation with as little harm to yourself as possible. Yes, you will be scared. Yes, you might indeed get hurt. Yes, it is possible that you could fail to defend yourself... but not for lack of trying. If the bad guy will not let you withdraw or de-escalate the situation, if he insists on fighting then he has decided that someone is going to get hurt. But it is you, not him, that gets to decide who.”
― Martin Dougherty, Special Forces Unarmed Combat Guide: Hand-to-Hand Fighting Skills From The World's Most Elite Military Units

“Even if you cannot achieve much in the way of fitness, every little [bit] helps. The other guy might be getting tired too. If he has five seconds' worth of fight left in him and you have 10, you will win.”
― Martin Dougherty, Special Forces Unarmed Combat Guide: Hand-to-Hand Fighting Skills From The World's Most Elite Military Units